This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Ancient pueblos built into the base of a natural canyon wall.

A geological mystery on Camelback Mountain.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

This lovely burial mound is actually a replica that was installed after archeologists excavated the original.

A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Quite simply the largest tree in the world (by volume).

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

The oldest badlands in North America, Makoshika State Park takes it name from the Lakota words for broken land.

Home to the deepest rift anywhere on Earth.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The first declared National Monument in the United States.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A beautiful geyser under environmental threat.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The only road through the heart of Glacier National Park.

An apocalyptic seismic event creates a deadly chain reaction that ends with a 6-mile long lake developing within weeks.

The last physical evidence of the Lewis and Clark trail is one of their autographs etched into this giant rock.

This giant meditative chakra sits peacefully in the Flathead Valley of western Montana.

An entire town preserved as a historic landmark.

A smoke stack so large, the Washington Monument could fit inside!